1.1 --- a/src/Provers/Arith/cancel_factor.ML	Wed Jul 28 11:42:48 2010 +0200
     1.2 +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.3 @@ -1,70 +0,0 @@
     1.4 -(*  Title:      Provers/Arith/cancel_factor.ML
     1.5 -    Author:     Markus Wenzel and Stefan Berghofer, TU Muenchen
     1.6 -
     1.7 -Cancel common constant factor from balanced exression (e.g. =, <=, < of sums).
     1.8 -*)
     1.9 -
    1.10 -signature CANCEL_FACTOR_DATA =
    1.11 -sig
    1.12 -  (*abstract syntax*)
    1.13 -  val mk_sum: term list -> term
    1.14 -  val dest_sum: term -> term list
    1.15 -  val mk_bal: term * term -> term
    1.16 -  val dest_bal: term -> term * term
    1.17 -  (*rules*)
    1.18 -  val prove_conv: tactic -> tactic -> Proof.context -> term * term -> thm
    1.19 -  val norm_tac: tactic (*AC0 etc.*)
    1.20 -  val multiply_tac: integer -> tactic
    1.21 -    (*apply a ~~ b  ==  k * a ~~ k * b  (for k > 0)*)
    1.22 -end;
    1.23 -
    1.24 -signature CANCEL_FACTOR =
    1.25 -sig
    1.26 -  val proc: simpset -> term -> thm option
    1.27 -end;
    1.28 -
    1.29 -
    1.30 -functor CancelFactorFun(Data: CANCEL_FACTOR_DATA): CANCEL_FACTOR =
    1.31 -struct
    1.32 -
    1.33 -
    1.34 -(* count terms *)
    1.35 -
    1.36 -fun ins_term (t, []) = [(t, 1)]
    1.37 -  | ins_term (t, (u, k) :: uks) =
    1.38 -      if t aconv u then (u, k + 1) :: uks
    1.39 -      else (t, 1) :: (u, k) :: uks;
    1.40 -
    1.41 -fun count_terms ts = foldr ins_term (sort Term_Ord.term_ord ts, []);
    1.42 -
    1.43 -
    1.44 -(* divide sum *)
    1.45 -
    1.46 -fun div_sum d =
    1.47 -  Data.mk_sum o maps (fn (t, k) => replicate (k div d) t);
    1.48 -
    1.49 -
    1.50 -(* the simplification procedure *)
    1.51 -
    1.52 -fun proc ss t =
    1.53 -  (case try Data.dest_bal t of
    1.54 -    NONE => NONE
    1.55 -  | SOME bal =>
    1.56 -      (case pairself Data.dest_sum bal of
    1.57 -        ([_], _) => NONE
    1.58 -      | (_, [_]) => NONE
    1.59 -      | ts_us =>
    1.60 -          let
    1.61 -            val (tks, uks) = pairself count_terms ts_us;
    1.62 -            val d = 0
    1.63 -              |> fold (Integer.gcd o snd) tks
    1.64 -              |> fold (Integer.gcd o snd) uks;
    1.65 -          in
    1.66 -            if d = 0 orelse d = 1 then NONE
    1.67 -            else SOME
    1.68 -              (Data.prove_conv (Data.multiply_tac d) Data.norm_tac (Simplifier.the_context ss)
    1.69 -                (t, Data.mk_bal (div_sum d tks, div_sum d uks)))
    1.70 -          end));
    1.71 -
    1.72 -
    1.73 -end;